Legionellosis

Question 1

Is legionellosis nationally notifiable?

Answer 1

Yes. Urgent response.

Question 2

What causes legionellosis?

Answer 2

Legionella species bacteria.
L. pneumophilia and L. longbeachae

Ubiquitous environmental organisms. Imporant causes of CAP and HAP.

Question 3

How is legionella transmitted?

Answer 3

Inhalation of contaminated aerosols of water/dust.

Pneumophilia - air-conditioning cooling towers, whirlpool spas, showers, fountains
Longbaechae - garden soil, potting mix

Question 4

What are the clinical features of legionellosis?

Answer 4

Spectrum of disease.
Asymptomatic
Mild (cough. fever)
Severe (rapid progressing pneumonia, multi-organ failure)

Question 5

Who are high-risk groups for legionellosis?

Answer 5

Elderly, chronic disease, immunocompromised, smokers.

Question 6

What are the case definitions for legionellosis?

Answer 6

Confirmed: lab definitive + clinical
Probable: lab suggestive + clinical

Clinical = fever, cough pneumonia
Lab definitive = isolation, urinary antigen, seroconversion
Lab suggestive = single high titre, NAT, DFA

Question 7

How is legionellosis diagnosed?

Answer 7

• Urinary antigen testing
• Serology
• Culture
• NAT

Reference lab: VIDRL - typing, genotyping

Question 8

What is the incubation period for legionellosis?

Answer 8

5 - 6 days (average)

Generally 2-10; outliers 1-28

Question 9

What is the infectious period for legionellosis?

Answer 9

NA - no person-person transmission.

Question 10

What is the outbreak definition for legionellosis?

Answer 10

Cluster = 2 + cases linked geographically

Outbreak = 2 + cases linked in time with epi evidence of common source (or 1 nosocomial)

Question 11

Where can Legionella bacteria be found naturally?

Answer 11

Ubiquitous in environment - soil / water.

Thrive in closed water systems (20-43 C).

Question 12

How is legionellosis from water sources prevented?

Answer 12

Minimise risk in cooling towers and warm water sources through maintenance, water quality, education of building operators, legislation, enforcement.

Use sterile water to clean rebuliser medication chambers and to prepare aerosol solutions for use in nebulisers and humidifiers.

Question 13

How is legionellosis from soil sources prevented?

Answer 13

Education - gardening hygiene (gloves, handwashing, moistening potting mix, warning labels)

Question 14

Who regulates cooling towers in Tasmania?

Answer 14

Local councils under the Public Health Act 1997

Question 15

What are some resources to manage legionellosis from a public health perspective?

Answer 15

CDNA SoNG, Tas DoH protocol

Question 16

How are cases of legionellosis managed?

Answer 16

• Contact clinician
• Interview case (sx, rfs, exposure hx 2-10 days prior,
• Map movements - hospital, RACF, shops, malls, pools, spars, cinemas, clubs, car was, humidifer/nebuliser use, travel, gardening)

Question 17

How are contacts of legionellosis managed?

Answer 17

N/A.

Active case-finding if suspected workplace source, cluster/outbreak or if case spent incubation period in high-risk setting (hospital/RACF), or if high-risk source identified e.g. cooling tower.

Question 18

What is the environmental management of legionellosis?

Answer 18

• Environmental evaluation
• Check cooling tower registers
• Test suspected cooling towers/other sources
• Disinfection of source in accordance with regulations

Question 19

Who are some other stakeholders that may need to be involved in legionellosis management?

Answer 19

WorkSafe,
IPC teams in healthcare settings

Question 20

What are some additional considerations in a legionella outbreak?

Answer 20

• Map case movements
• Urgent environmental evaluation
• Match case and environmental isolates
• Active surveillance - GP/ID/Resp/ED for CAP
• Communications